1) Field of the Invention
The present invention is related to ultrasonic welding devices, and more particularly, to an apparatus for providing pressure to a component during the ultrasonic welding process.
2) Description of Related Art
Ultrasonic welding apparatuses are commonly used to join one or more components by producing mechanical vibrations that are absorbed by the component and that heat the material of the component to a melting point and/or to a state where an applied pressure allows the component to be joined. For example, plastics are ultrasonically welded by positioning the plastic component adjacent an ultrasonic horn, through which the ultrasonic vibrations produced by an ultrasonic transducer are transmitted. The plastic component absorbs the ultrasonic vibrations, such that the material plasticizes locally. The plasticized material can therefore be joined to other material. Ultrasonic welding is widely used with plastics because it may be performed relatively quickly and usually produces welds that are relatively free of flash. Ultrasonic welding may also be used with other materials such as metals.
During the ultrasonic welding process, pressure is typically applied to the component being welded. Such pressure ensures that one or more components are properly joined during the relatively brief period of time that the material is heated. Therefore, applying pressure to the component is an important aspect of ultrasonic welding. However, when components defining unusual shapes or sizes require ultrasonic welding, providing the proper pressure to the component can be complicated. One example of such a component is a rolled sheet being welded into a tube. One technique for providing the proper amount of pressure is to insert a rigid arm into the interior of the tubular component so that the an applies a pressure on the component proximate the ultrasonic transducer and horn. This technique is often undesirable because of the required amount of fixturing, the difficulty in applying the proper amounts of pressure, the time involved to properly position the an, and/or the inability of an arm to provide adequate amounts of pressure at hard-to-reach locations on die component. Accordingly, a need exists for an apparatus that conveniently provides pressure to a component during ultrasonic welding.